#3789: Segfault and -dstg-lint errors using FFI and -XEmptyDataDecls
------------------------+---------------------------------------------------
Reporter: judahj | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler (NCG)
Version: 6.12.1 | Keywords:
Os: MacOS X | Testcase:
Architecture: x86 | Failure: Runtime crash
------------------------+---------------------------------------------------
I encountered a segfault when working with some FFI code. I eventually
discovered that this code also makes `-dstg-lint` complain.
With the below files, I can reproduce the segfault and `-dstg-lint` issues
using ghc-6.12.1 and ghc-6.10.3 on OS X 10.6.2. The segfault goes away if
I use -fvia-C, -O, or if I build on OS X 10.5.7.
The segfault also goes away if I use a unit type `()` instead of
-XEmptyDataDecls.
{{{
$ ghc --make test-segfault.hs foreign.c -XForeignFunctionInterface \
-XEmptyDataDecls -fforce-recomp && ./test-segfault
[1 of 2] Compiling Types ( Types.hs, Types.o )
[2 of 2] Compiling Main ( test-segfault.hs, test-segfault.o )
Linking test-segfault ...
About to create...
Segmentation fault
}}}
foreign.c:
{{{
#include <stdio.h>
#include <stdlib.h>
void *
c_createFoo (int x) {
fprintf(stderr,"Creating foo...\n");
fflush(stderr);
int *p = malloc(sizeof(int));
*p = x;
return p;
}
}}}
Types.hs:
{{{
module Types where
import Foreign.Ptr
import Foreign.C.Types
-- Replacing this line with the following one prevents the segfault,
-- but not the -dstg-lint error.
data Foo_
-- type Foo_ = ()
foreign import ccall safe c_createFoo :: CInt -> IO (Ptr Foo_)
createFoo :: Int -> IO (Ptr Foo_)
createFoo dtype = c_createFoo (toEnum dtype)
}}}
test-segfault.hs:
{{{
module Main where
import Types
main = do
putStrLn "About to create..."
createFoo 1
putStrLn "Created."
}}}
The `-dstg-lint` error is somewhat long, but I can paste it if you're
unable to reproduce it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3789>
GHC <http://www.haskell.org/ghc/>
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